:root {
  --bg: #f6f5f1;          /* paper */
  --panel: #ffffff;
  --ink: #1f2328;
  --muted: #6b7280;
  --line: #e4e2dc;
  --accent: #2563eb;
  --accent-soft: #eaf0ff;
  --A: #2e7d32; --B: #b26a00; --C: #c62828;   /* difficulty colors */
  --star: #d39e00;
  --drawer: 270px;
  --header: 48px;
}
* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0; color: var(--ink); background: var(--bg);
  font-family: "BIZ UDPGothic", "Hiragino Kaku Gothic ProN", "Noto Sans JP", system-ui, sans-serif;
  font-size: 15px; line-height: 1.7;
}

/* ---------- header (slim) ---------- */
header {
  position: sticky; top: 0; z-index: 30;
  background: var(--panel); border-bottom: 1px solid var(--line);
  height: var(--header); padding: 0 12px; display: flex; align-items: center; gap: 10px;
  padding-top: env(safe-area-inset-top, 0);
}
.menu {
  border: 1px solid var(--line); background: var(--bg); color: var(--ink);
  border-radius: 8px; width: 34px; height: 32px; font-size: 16px; cursor: pointer; flex: none;
}
.menu:active { background: var(--accent-soft); }
.brand { font-weight: 700; font-size: 15px; white-space: nowrap; }
.brand .sub { color: var(--muted); font-weight: 400; font-size: 12px; margin-left: 4px; }
.exam-select {
  border: 1px solid var(--line); border-radius: 8px; padding: 5px 8px; font-size: 13px;
  background: var(--panel); color: var(--ink); max-width: 46vw; font-variant-numeric: tabular-nums;
}
.review { color: var(--muted); font-size: 13px; cursor: pointer; user-select: none; margin-left: auto; white-space: nowrap; }

/* ---------- off-canvas drawer ---------- */
.scrim {
  position: fixed; inset: 0; background: rgba(0,0,0,.32); z-index: 35;
  opacity: 0; pointer-events: none; transition: opacity .2s;
}
.scrim.show { opacity: 1; pointer-events: auto; }
.drawer {
  position: fixed; top: 0; left: 0; z-index: 36;
  width: var(--drawer); max-width: 84vw; height: 100vh; overflow-y: auto;
  background: var(--panel); border-right: 1px solid var(--line);
  padding: calc(env(safe-area-inset-top, 0) + 12px) 10px 24px;
  transform: translateX(-100%); transition: transform .22s ease;
  box-shadow: 0 0 40px rgba(0,0,0,.12);
}
.drawer.open { transform: none; }
.drawer-section { margin-bottom: 12px; }
.drawer-label { font-size: 11px; color: var(--muted); font-weight: 700; margin: 4px 4px 6px; letter-spacing: .04em; }
.seg { display: inline-flex; border: 1px solid var(--line); border-radius: 8px; overflow: hidden; }
.seg button { border: 0; background: var(--panel); padding: 6px 14px; cursor: pointer; font-size: 14px; color: var(--ink); }
.seg button + button { border-left: 1px solid var(--line); }
.seg button.on { background: var(--accent-soft); color: var(--accent); font-weight: 700; }
#field-filter { width: 100%; border: 1px solid var(--line); border-radius: 8px; padding: 6px 8px; font-size: 14px; background: var(--panel); }

/* ---------- layout ---------- */
main { display: block; }
.index { padding: 2px 0; }
.index .row {
  display: flex; align-items: center; gap: 10px; padding: 9px 8px; border-radius: 7px;
  cursor: pointer; font-size: 14px; color: var(--ink); white-space: nowrap;
}
.index .row:hover { background: var(--accent-soft); }
.index .row.active { background: var(--accent-soft); color: var(--accent); font-weight: 700; }
.index .row.no-notes { color: var(--muted); }
.badge {
  font-size: 10.5px; font-weight: 700; width: 16px; text-align: center;
  border-radius: 4px; color: #fff; flex: none;
}
.badge.A { background: var(--A); } .badge.B { background: var(--B); } .badge.C { background: var(--C); }
.badge.x { background: var(--line); color: var(--muted); }

.doc { padding: 18px 28px 60vh; max-width: 880px; margin: 0 auto; }
.doc h1 { font-size: 19px; margin: 6px 0 18px; }
@media (max-width: 760px) {
  .doc { padding: 14px 16px 70vh; }
  /* stack: screenshot first, then text */
  .step { grid-template-columns: 1fr; gap: 8px; }
  .step img { max-width: 100%; }
  /* full-width bottom-sheet video player */
  .player {
    left: 0; right: 0; bottom: 0; width: 100%; max-width: none;
    border-radius: 12px 12px 0 0;
    padding-bottom: env(safe-area-inset-bottom, 0);
  }
  .player video { max-height: 46vh; object-fit: contain; }
}

/* ---------- problem block ---------- */
.problem { padding: 14px 0 20px; border-top: 2px solid var(--line); scroll-margin-top: calc(var(--header) + 8px); }
.problem:first-child { border-top: 0; }
.p-head { display: flex; align-items: baseline; gap: 10px; margin-bottom: 8px; }
.p-title { font-size: 17px; font-weight: 700; }
.p-meta { color: var(--muted); font-size: 12.5px; }
.p-actions { margin-left: auto; display: flex; gap: 8px; align-items: center; }
.plink {
  text-decoration: none; font-size: 13px; color: var(--muted);
  border: 1px solid var(--line); border-radius: 7px; padding: 3px 8px; line-height: 1.4;
}
.plink:hover { border-color: var(--accent); color: var(--accent); }
.vbtn {
  border: 1px solid var(--line); background: var(--panel); border-radius: 7px;
  padding: 3px 10px; font-size: 12.5px; cursor: pointer; color: var(--accent);
}
.vbtn:hover { border-color: var(--accent); }
.vbtn[disabled] { color: var(--muted); cursor: default; border-style: dashed; }

.statement { background: var(--panel); border: 1px solid var(--line); border-radius: 8px; padding: 10px 14px; }
.answer { margin-top: 8px; font-size: 14px; }
.answer b { color: var(--A); }

.steps { margin-top: 10px; display: flex; flex-direction: column; gap: 12px; }
.step { display: grid; grid-template-columns: minmax(0, 320px) 1fr; gap: 14px; align-items: start; }
.step img {
  width: 100%; border: 1px solid var(--line); border-radius: 6px; background: #fff;
  cursor: pointer; display: block;
}
.step .txt { font-size: 14.5px; }
.step .ts { color: var(--accent); font-size: 12px; cursor: pointer; font-variant-numeric: tabular-nums; }
.step.no-shot { grid-template-columns: 1fr; }

.takeaways { margin-top: 12px; background: #fffdf3; border: 1px solid #f0e6c0; border-radius: 8px; padding: 8px 14px; }
.takeaways .t { display: flex; gap: 8px; align-items: baseline; padding: 3px 0; font-size: 14px; }
.takeaways .star { color: var(--star); }
.takeaways .ts { color: var(--accent); font-size: 12px; cursor: pointer; }

.points { margin-top: 10px; font-size: 13px; color: var(--muted); }
.points a { color: var(--accent); text-decoration: none; margin-right: 12px; }
.points a:hover { text-decoration: underline; }

.inline-video { margin-top: 10px; }
.inline-video video { width: 100%; max-width: 560px; border-radius: 8px; background: #000; }

.unprocessed { color: var(--muted); font-style: italic; font-size: 13px; margin-top: 6px; }

/* review mode: hide step detail, keep statement/answer/takeaways */
body.review .steps { display: none; }

.hint {
  position: fixed; bottom: 12px; left: 50%; transform: translateX(-50%);
  background: rgba(31,35,40,.85); color: #fff;
  font-size: 12px; padding: 6px 10px; border-radius: 7px; pointer-events: none;
  opacity: 0; transition: opacity .3s;
}
.hint.show { opacity: 1; }

/* docked, persistent video player */
.player {
  position: fixed; bottom: 14px; right: 14px; width: 420px; max-width: 46vw;
  background: #000; border-radius: 10px; overflow: hidden; z-index: 40;
  box-shadow: 0 8px 30px rgba(0,0,0,.35); border: 1px solid var(--line);
}
.player.hidden { display: none; }
.player-bar {
  display: flex; align-items: center; gap: 8px; padding: 5px 8px;
  background: #1f2328; color: #fff; font-size: 12.5px;
}
.player-bar #player-title { flex: 1; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.player-bar button {
  border: 0; background: transparent; color: #cbd2da; cursor: pointer; font-size: 14px; padding: 2px 6px; border-radius: 5px;
}
.player-bar button:hover { background: #333a44; color: #fff; }
.player video { width: 100%; display: block; background: #000; }